wind instruments such as the flute, oboe, and bassoon were readmitted to counteract the monotony of hearing only strings. In the mid-seventeenth century, what was known as a hunter's horn underwent a transformation into an "art instrument" consisting of a lengthened tube, a narrower bore, a wider bell, and a much wider range. The details of this transformation are unclear, but the modern horn or, more colloquially, French horn, had emerged by 1725. The slide trumpet appeared, a variation that includes a long-throated mouthpiece that slid in and out, allowing the player infinite adjustments in pitch. This variation on the trumpet was unpopular due to the difficulty involved in playing it. Organs underwent tonal changes in the Baroque period, as manufacturers such as Abraham Jordan of London made the stops more expressive and added devices such as expressive pedals. Sachs viewed this trend as a "degeneration" of the general organ sound. Classical and Romantic During the Classical and Romantic periods of music, lasting from roughly 1750 to 1900, many musical instruments capable of producing new timbres and higher volume were developed and introduced into popular music. The design changes that broadened the quality of timbres allowed instruments to produce a wider variety of expression. Large orchestras rose in popularity and, in parallel, the composers determined to produce entire orchestral scores that made use of the expressive abilities of modern instruments. Since instruments were involved in collaborations of a much larger scale, their designs had to evolve to accommodate the demands of the orchestra. Some instruments also had to become louder to fill larger halls and be heard over sizable orchestras. Flutes and bowed instruments underwent many modifications and design changes—most of them unsuccessful—in efforts to increase volume. Other instruments were changed just so they could play their parts in the scores. Trumpets traditionally had a "defective" range—they were incapable of producing certain notes with precision. New instruments such as the clarinet, saxophone, and tuba became fixtures in orchestras. Instruments such as the clarinet also grew into entire "families" of instruments capable of different ranges: small clarinets, normal clarinets, bass clarinets, and so on. Accompanying the changes to timbre and volume was a shift in the typical pitch used to tune instruments. Instruments meant to play together, as in an orchestra, must be tuned to the same standard lest they produce audibly different sounds while playing the same notes. Beginning in